Broadway-bred musical revives karaoke classics.

Film-wise, I've dreaded few things more this year than the prospect of watching Tom Cruise play '80s metal god "Stacee Jaxx" in the Broadway-goes-big-screen musical Rock of Ages. As unfathomable as this looked in preview form, though, I probably shouldn't be surprised to report that Cruise's performance is one of the more worthwhile aspects of a mostly disposable film.

As with Cruise's vulgar Hollywood producer cameo in Tropic Thunder and his supporting turn as a self-help monster in Magnolia, the ego-driven meticulousness and dedication of the performance matters. So many other easily imaginable comedic stunt-casting options — Adam Sandler, anyone? — would have stumbled through this role as an easy joke. But Cruise's android perfectionism is helpful here: He studies those Axl Rose poses until he gets them just right and is at his most oddly compelling when director Adam Shankman puts him onstage or allows his character to function in quasirealistic settings.

There's a whole lot more going on in this noisy, chaotic, overpopulated jukebox musical — a recent, minor Broadway hit built around "hair metal" and radio-rock hits from the '80s. Set on Sunset Strip circa 1987, it's The Decline of Western Civilization Part II: The Metal Years played as sanitized, PG-13 comedy. At the center of the plot are a pair of young hopefuls — sweet-tempered, fresh-off-the-bus Oklahoman Sherrie (Footloose's engaging Julianne Hough) and too-clean-cut rocker Drew (Diego Boneta, a younger, more bland Matthew McConaughey lookalike) — who meet-cute early and follow their rock-star dreams as waitress and bar-back, respectively, at the Strip's rock temple, the Bourbon Room.

Despite the Oscar win of Chicago a decade ago and the artistic and musicological improvement of Dreamgirls a few years later, the recent, seemingly growing spate of films based on Broadway musicals hasn't been particularly fruitful, and the cheap, flashy, sometimes fun but more often "fun" Rock of Ages doesn't reverse that trend.

There are other snatches of interesting activity surrounding Cruise's performance. Paul Giamatti is good in everything, and so he is here as Cruise's skeevy manager. Horror auteur Eli Roth has a brief, intense turn as a music-video director. And sometimes the music saves everything, or comes close: Though the actor's vocals are most often too American Idol and not enough Sunset Strip, the pop-metal milieu is well-suited to this kind of project. These aren't classic records, by and large. But they're definitely karaoke classics.

Missteps are many: The execrable Jefferson Starship anthem "We Built This City" becomes the rallying cry of the rockers in a bit of street theater that might have you wanting to cross over to enemy lines. A comic side plot involving a New Kids on the Block-style boy band is too easy and muddles the action. Mary J. Blige is underused as a strip-club operator who doesn't get a real vocal showcase despite being, by far, the best singer in the film. Catherine Zeta-Jones gives an uncomfortable performance as a Michele Bachmann/Tipper Gore hybrid crusader, including a cringe-inducing between-the-church-pews song-and-dance routine to Pat Benatar's "Hit Me With Your Best Shot."

More than anything, this film version of a Broadway musical about rock music is too much Broadway and too little rock-and-roll, in both sound and temperament.